Okay. So, I want to build something along the lines of this... http://www.instructables.com/id/Music-LED-Light-Box/
In that Instructable, the 6 LEDs are wired in series. I want to be able to wire them in parallel and replace the 12V DC adapter with a USB connector so that the box may be powered via my laptop's USB port. This way I won't need another cable going off to a power point in the wall and things will be nice and tidy around my laptop.

Now, I know that the USB 2.0 ports (which is what my laptop has) are 5V @ 500mA.

So that's pretty much 6000MCD 3.8V LEDs @ 30mA, correct? And this guy here: http://www.youtube.com/watch?v=svWz3xQkkx4&feature=related has his version of the LED music light box USB powered. Would I be correct in saying that this USB powered version still needs the 3.5mm connection to the audio output, just as the 12V DC powered version does?

So, in other words, I chuck the 12V DC adapter out and hook it up to a USB connector instead, stick a 47 ohm resistor in before each LED, then hook up the 6 LEDs in parallel and it goes. If any of what I said was correct, it should work, right ?

If anybody has any suggestions, comments or improvements, advice, please feel free to share!

So that's pretty much 6000MCD 3.8V LEDs @ 30mA, correct? And this guy here: http://www.youtube.com/watch?v=svWz3xQkkx4&feature=related has his version of the LED music light box USB powered. Would I be correct in saying that this USB powered version still needs the 3.5mm connection to the audio output, just as the 12V DC powered version does?

You need a controller chip that is programmed to change the music to the beat. You can buy smallish controllers on ebay where you might be able to take the circuit board out. Ether way you will need an audio input ether a line in or a small microphone.